Solar heat-shielding coating composition and coated structure

ABSTRACT

This invention relates to a solar heat-shielding coating composition which consists mainly of two kinds or more of pigments selected from red, orange, yellow, green, blue and purple pigments in such a manner as to yield a color of low lightness, particularly achromatic black, by additive mixture and a weather-resistant vehicle and a structure covered with said coating composition, with the composition capable of covering the outside of said structure exposed directly to the sun and suppressing a rise in the inside temperature.

FIELD OF TECHNOLOGY

This invention relates to a solar heat-shielding coating composition anda coated structure and, more particularly, to a coating compositionwhich is suitable for covering ocean structures, decks and tanks ofships, outdoor structures such as cylindrical or spherical tanks,buildings such as houses, commercial offices, warehouses and gymnasiums,outdoor structures such as automobiles, tank lorries, and cold-storagecontainers and home electrical appliances such as refrigerators to keepthe inside temperature from rising by direct rays of the sun, to enhancethe effects of air conditioning or refrigeration and to realize savingin energy or prevent evaporation of the volatile components of oils andalso to a structure coated therewith.

BACKGROUND TECHNOLOGY

There has been a strong demand for saving of the air-conditioning costof buildings by preventing an increase of the inside temperature causedby the solar rays, for reducing the evaporation loss of volatiles fromoil tankers, natural gas transport ships, and tanks installed on land bycoating the outer surface of these facilities and for improvingrefrigerating efficiency of tanks and home electrical appliances. Forexample, the loss of crude oils by evaporation from tankers is enormousand it is said to amount to 0.2 to 0.5% of the total load in one voyagefrom the Near East or the Middle East to Japan.

To deal with the above-mentioned problems, white pigments such astitanium oxide and colored pigments have hitherto been used in solarheat-shielding coatings. Coloring in white produces a solarheat-shielding effect to some extent, but coloring in other than whiteleads to a marked reduction of this effect. In consequence, there is ademand for availability of coating compositions in any desired color ofa good solar heat-shielding effect.

On the other hand, aluminum paints containing scaly aluminum powdershave been known as solar heat-shielding coatings for the roofs ofbuildings and the outer surface of tanks. These paints are available ina limited number of colors and do not possess sufficient durability and,besides, they are not suitable for the places to be walked on because oftheir poor abrasion resistance.

Heat-reflective enamels containing antimony trioxide, antimonydichromate, alkali metal dichromates and the like are proposed in JapanKokai Tokkyo Koho No. Sho 56-109,257 (1981) to solve the above-mentionedproblems. They are, however, not desirable from the viewpoint ofenvironmental sanitation as they contain heavy metals.

Processes for the manufacture of metal plates covered with emulsioncoatings containing fine glass powders with a particle diameter of 20 to350 μm, coatings containing synthetic silica powders and white pigmentswith a particle diameter of 300 μm or less or coatings containing groundglass with a particle diameter of 5 to 300 μm are proposed in JapanTokkyo Koho No. Sho 55-33,828 (1980) and Japan Kokai Tokkyo Koho Nos.55-120,669 (1980) and 55-74,862 (1980). Theses coatings exhibit anexcellent solar heat-shielding effect in the initial stage, but theysuffer a marked loss of this effect with the passage of time as theyhave an uneven texture on their surface and show poor long-termantisoiling properties. Hence, it was difficult for this type ofcoatings to be safe and colorable in any desired color and to maintainthe solar heat-shielding effect for an extended period of time.

Such being the case, the present inventors already proposed in JapanKokai Tokkyo Koho No. Hei 1-121,371 (1989) that (1) one or more ofzirconium oxide, yttrium oxide and indium oxide and (2) compounds of oneor more of zirconium oxide, indium oxide, titaniumm oxide and siliconoxide and one or more of magnesium oxide, yttrium oxide, barium oxide,calcium oxide and zinc oxide are substances capable of meeting theabove-mentioned property requirements.

The present inventors also proposed in Japan Kokai Tokkyo Koho No. Hei1-263,163 (1989) to use Si or an alloy or alloys of Si and one or moreof Al, Fe, Mg, Mn, Ni, Ti, Cr and Ca with a particle diameter of 50 μmor less as solar heat-shielding pigments for achromatic gray such asMunsell color notation N-2 to N-7. Moreover, they proposed the use ofcolored pigments based on complex oxides for chromatic color in JapanKokai Tokkyo Koho No. Hei 2-185,572 (1990). The technologies thusdisclosed have made it possible to provide compositions and structureswith solar heat-shielding effects for white, achromatic gray, andchromatic color. Coloring in black for which the largest effect isexpected, however, requires the use of carbon black, iron black, copperchrome black and the like and this was bound to lower the solarheat-shielding effect.

It is an object of this invention to provide a black coating compositionwhich covers the surface of a variety of structures on land and sea,ships, buildings, and home electrical appliances exposed to direct solarrays to prevent a rise of the inside temperature thereby reducing theair-conditioning cost or loss by evaporation of the contents for amarked saving in energy and is serviceable with long-term durability,free of problems relating to environmental sanitation, and of goodappearance and to provide a structure coated therewith.

DISCLOSURE OF THE INVENTION

The present inventors have conducted extensive studies to solve theabove-mentioned problems, found that a coating composition containingtwo kinds or more of red, orange, yellow, green, blue and purpolepigments with a particle diameter of 50 μm or less showing high solarradiation reflectance in the ultraviolet and near infrared regions insuch proportion as to yield a color of low lightness, particularlyachromatic black, by additive mixture shows excellent long-termdurability and effectiveness and arrived at this invention.

Accordingly, of coating compositions mainly consisting of vehicles andpigments, this invention relates to a solar heat-shielding coatingcomposition which comprises a weather-resistant vehicle and a solarheat-shielding pigment consisting of two kinds or more of pigmentsselected from (A) red pigments with a particle diameter of 50 μm or lessshowing a solar radiation reflectance of 45% or more in the range of 350to 2,100 nm calculated from the spectral reflectance (Rλi) as specifiedin JIS A 5759 for architectural films for shielding heat rays andpreventing scattering of shattered glass, (B) orange pigments with aparticle diameter of 50 μm or less showing a solar radiation reflectanceof 55% or more, (C) yellow pigments with a particle diameter of 50 μm orless showing a solar radiation reflectance of 60% or more, (D) greenpigments with a particle diameter of 50 μm or less showing a solarradiation reflectance of 20% or more, (E) blue pigments with a particlediameter of 50 μm or less showing a solar radiation reflectance of 20%or more and (F) purple pigments with a particle diameter of 50 μm orless showing a solar radiation reflectance of 35% or more in suchproportion as to yield a color of low lightness, particularly achromaticblack, by additive mixture, said pigments accounting for 2 to 60% byweight of the solids in said coating.

This invention also relates to a structure coated for solar heatshielding which comprises a coat of excellent solar heat reflectioncontaining a weather-resistant vehicle and two kinds or more of pigmentsselected from red, orange, yellow, green, blue and purple pigments witha particle diameter of 50 μm or less in such proportion as to yield acolor of low lightness, particularly achromatic black, by additivemixture at least on the outermost layer of the substrate of saidstructure and a coat mainly consisting of a heat-insulating filler and avehicle with good adhesiveness and corrosion resistance beneath theaforesaid solar heat-reflecting coat.

This invention will be described in detail below. In this invention, lowlightness means an L* value of 35 or less when the color is designatedby the CIELAB color system. As long as colors remain in this range oflow lightness, they include not only Munsell notation N-1 but alsoMunsell notation N-2 and N-3, slightly reddish color and greenish color.

A vehicle of excellent weather resistance useful for a coatingcomposition of this invention refers to the one which is durable withexcellent yellowing resistance, color retention, gloss retention andchalking resistance and can maintain the heat shielding effect for aprolonged period of time. Vehicles which dry at room temperature maydesirably be composed mainly of one or more of acrylic resins,silicone-modified polyesters, alkyd resins, silicone-modified alkydresins and fluorine-containing resins and combined, as needed, with oneor more of hexamethylene diisocyanate or its adducts, isophoronediisocyanate or its adducts, hydrogenated xylylene diisocyanate or itsadducts, hydrogenated dicyclohexylmethane diisocyanate or its adductsand tetramethylxylylene diisocyanate or its adducts or they may becomposed mainly of acrylic resins having carboxyl group and/or aminogroup and combined, as needed, with compounds having glycidyl group.Vehicles which are suitable for forced drying may desirably be composedmainly of one or more of polyesters, silicone-modified polyesters,fluorine-containing resins and acrylic resins and combined, as needed,with one or more of blocked isocyanates and melamine resins.

With respect to solar heat-shielding pigments useful for a compositionof this invention, it is desirable for said pigments to show, whileformulated in a coating, a high solar heat radiation reflectance in therange from 350 to 2,100 nm, particularly outside the range of visiblelight or below 380 nm and above 780 nm, as calculated from the spectralreflectance (Rλi) specified by JIS A 5759 for architectural films forshielding heat rays and preventing scattering of shattered glass, to besafe and water- and weather-resistant and maintain their heat-shieldingeffect for a prolonged period of time.

Extensive studies on pigments have indicated that not a black pigmentnormally used for coatings such as carbon black, iron black and copperchrome black but a pigment of low lightness, particularly achromaticblack, obtained by additive mixture of red, orange, yellow, green, blueand purple pigments produces an excellent effect. That is, it ispossible to obtain achromatic black by combining two or more of pigmentswhich are located opposite to each other in the hue circle shown in JISZ 8721 for specification of colors according to their three attributes,for example, by combining red and cyan or yellow and violet. The pigmentobtained in this manner is black with practically no reflection in thevisible light region with the wavelength ranging from 380 nm to 780 nmbut it is black with high reflective radiance (Munsell notation N-1) inthe near infrared region from 780 nm and upward.

As a concrete example, it is possible to obtain black of Munsellnotation N-1 by a combination of a red pigment based on equinacridone(PV19), a blue pigment based on copper phthalocyanine (PB15:4) and ayellow pigment based on benzimidazolone (PY154). It is also possible toobtain the same N-1 by a combination of a yellow pigment based onisoindoline (PY109) and a purple pigment based on dioxazine (PV23). Eachof the pigments thus prepared shows a solar radiation reflectance of 30%or more. Thus, N-1 black can yield an exceptionally large value of solarradiation reflectance compared with 0 to a few percent by carbon black,iron black or copper chrome black.

As described above, the substance of this invention is to prepare acolor of low lightness, particularly achromatic black, by additivemixture of red, orange, yellow, green, blue and purple for use in asolar heat-shielding coating composition without using black pigments.Pigments for additive mixture can be chosen in consideration of theirhue, weather resistance and color stability.

A red pigment can be chosen from the following pigments identifiable byPigment Red (PR) and Colour Index Pigment Number (C.I. No.) of Societyof Dyers and Colourists: PR3, PR5, PR48, PR58, PR88, PR112, PR122,PR123, PR144, PR149, PR165, PR168, PR170, PR171, PR175, PR177, PR178,PR179, PR187, PR189, PR190, PR194, PR202, PR207, PR209, PR214, PR216,PR224, PR242, PR253, PR254, PR260 and PR351.

An orange pigment can be chosen from the following pigments identifiableby Pigment Orange (PO) and C.I. No.: PO5, PO13, PO16, PO34, PO36, PO38,PO43, PO60, PO62, PO65 and PO69.

A yellow pigment can be chosen from the following pigments identifiableby Pigment Yellow (PY) and C.I. No.: PY1, PY3, PY13, PY14, PY16, PY17,PY24, PY42, PY55, PY73, PY74, PY81, PY83, PY93, PY94, PY95, PY97, PY98,PY105, PY108, PY109, PY110, PY116, PY117, PY120, PY128, PY129, PY130,PY137, PY138, PY139, PY147, PY151, PY153, PY154, PY155, PY165, PY173 andPY175.

A green pigment can be chosen, for example, from PG7, PG 10 and PG36where PG stands for Pigment Green and the number for C.I. No.

A blue pigment can be chosen, for example, from PB15:1, PB15:2, PB15: 3,PB15:4, PB15:6, PB16 and PB60 where PB stands for Pigment Blue and thenumber for C.I. No.

A purple pigment can be chosen, for example, from PV19, PV23 and PV257where PV stands for Pigment Violet and the number for C.I. No.

It is necessary for the above-mentioned solar heat-shielding pigments tohave a particle diameter of 50 μm or less, more particularly 10 μm orless, from the standpoint of antisoiling property, weather resistance,and color stability. Very small irregularity forms in the coat when apigment with a diameter in excess of 50 μm is used. Dusts and sootsadhere to the depressions to soil the surface and this makes itdifficult to maintain the solar heat-shielding effect.

It is necessary, moreover, that a pigment with the above-mentionedparticle diameter must be present to 2 to 60% by weight of the solids inthe coating. With less than 2% by weight of such pigment, the colorationbecomes insufficient and a thicker coat is required. On the other hand,with more than 60% by weight, an excessive amount of pigment in the coatadversely affects the chalking resistance, which results in poor weatherresistance.

The solids in the coating here means substances which do not volatilizeor evaporate. They are generally those components which form a coat and,concretely, they are pigments, resins in vehicles, and other additives.

A coating composition of this invention formulated as above is dissolvedor dispersed in an organic solvent and adjusted to a suitable viscositybefore use. An organic solvent of adequate applicability and dryingquality is chosen from hydrocarbons, alcohols, ether alcohols, ethers,esters, ester alcohols and ketones.

It is possible to use, as needed, planarization agents, ultravioletabsorbers, viscosity modifiers, curing catalysts, pigment dispersingagents, pigment sedimentation inhibitors and color segregationinhibitors.

The second substance of this invention is that a coat is formed at leaston the outermost layer of a substrate by the above-mentioned coatingcomposition and beneath this coat is formed a coat mainly consisting ofa filler of excellent thermal insulation and a vehicle of excellentadhesiveness and corrosion resistance.

A coating composition to be applied to the outermost layer is asdescribed above and an excellent performance is obtained by applying thecomposition to a thickness of 1 μm or more, preferably 10 μm or more.With a thickness of less than 1 μm, the underlying coat exerts a toostrong influence to suppress the full performance of the coat inquestion. On the other hand, a good effect can be maintained up to afairly large thickness. Since the effect levels off with an increasingthickness, a thickness of 10 to 100 μm is desirable for the upper limit.

A filler of good thermal insulation to be contained in the underlyingcoat is preferably a scaly substance and/or a spherical hollowsubstance. It is possible to use glass flake or mica with a particlediameter of 50 μm or less as a scaly substance.

Scaly metals, for example, stainless steel foils and aluminum foils areon the market, but glass flake and mica are preferable in respect tothermal conductivity. The particle size of a scaly substance ispreferably 50 μm or less, more preferably 20 μm or less. With a particlesize of more than 50 μm a scaly substance produces unevenness in thecoat and adversely affects the overlying coat on the one hand andreduces the effects of thermal insulation and corrosion resistancebecause of its inability of flat arrangement on the other. With aparticle size of 20 μm or less, the ratio of scaly substance to vehicleis set at an appropriate value which allows parallel arrangement ofscales and the coat. This results in the formation of a dense layerwhich lengthens the path of water permeation or produces the so-calledlabyrinth effect and contributes to improvement of not only thecorrosion resistance but also the heat resistance.

It is also possible to use glass balloons, shirasu balloons or balloonsof resins such as polystyrene with a particle diameter of 50 μm or less,preferably 1 to 10 μm, as a spherical hollow substance. Balloons with adiameter in excess of 50 μm produce unevenness in the coat and adverselyaffect the overlying coat as described above. With a diameter of lessthan 1 μm, the effect of hollowness, namely, the effect of thermalinsulation decreases.

A vehicle to be used in the underlying coat consists mainly of one ormore of epoxy resins, modified epoxy resins, phenol-modified butyralresins, polyesters, acrylic resins, silicone-modified polyesters, alkydresins, fluoropolymers and polyurethanes, each with excellentadhesiveness and corrosion resistance, and curing agents, curingaccelerators, planarization agents, viscosity modifiers, pigmentdispersing agents, pigment sedimentation inhibitors and colorsegregation inhibitors are used as needed. Examples of curing agents areisocyanate group-containing compounds, amino group-containing compoundsand melamine resins.

It is desirable for the coat to contain 2 to 60% by weight of theabove-mentioned fillers. The effect of thermal insulation is notobtained with less than 2% of fillers while the coat loses adhesivenessand affects the overlying coat adversely with more than 60% of fillers.It is desirable for the underlying coat to contain 20 to 60% by weightof the above-mentioned vehicle. The adhesiveness of the coat becomespoor with less than 20% of the vehicle while the thermal insulation andcorrosion resistance decrease with more than 60% of the vehicle.

As described above, a structure of this invention has a coat ofexcellent solar heat reflection as the outermost layer and a coat ofexcellent thermal insulation beneath it. In this case, it is needless tosay that the underlying coat can be provided directly on the surface ofa structural substrate or a primer may be used between the two in orderto improve the adhesion of the two.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic diagram of a device used in the examples fordetermining the temperature of the reverse side of a specimen.

LEGEND

1Coat

2Steel plate

3Polystyrene foam block

4Incandescent lamp

5Electric power source

6Temperature sensor

7Temperature recorder

PREFERRED EMBODIMENTS OF THE INVENTION

This invention will be described concretely with reference to theaccompanying examples and comparative examples.

[Ingredients for Formulation]

1 Solar Mat-shielding pigments

Solar heat-shielding pigment A: FASTOGEN SUPER RED 7061B (PV19); averageparticle diameter 0.3 μm; product of Dainippon Ink and Chemicals, Inc.

Solar heat-shielding pigment B: FASTOGEN SUPER BLUE GNPM-K (PB15:4);average particle diameter 0.1 μm; product of Dainippon Ink andChemicals, Inc.

Solar heat-shielding pigment C: SYMULER FAST YELLOW 4192 (PY154);average particle diameter (long diameter) 0.4 μm; product of DainipponInk and Chemicals, Inc.

Solar heat-shielding pigment D: FASTOGEN GREEN S (PG7); average particlediameter (long diameter) 0.06 μm; product of Dainippon Ink andChemicals, Inc.

Solar heat-shielding pigment E: IRGAZIN YELLOW 2GLT (PY109); averageparticle diameter (long diameter) 2.5 μm; product of Ciba-Geigy

Solar heat-shielding pigment F: FASTOGEN SUPER VIOLET RN-S (PV23);average particle diameter (long diameter) 0.3 μm; product of DainipponInk and Chemicals, Inc.

2 Black pigments

Black pigment G: Carbon Black MA-100 (Pigment Black 6); average particlediameter 0.02 μm; product of Mitsubishi Kasei Corporation

Black pigment H: Iron Black BL-100 (Pigment Black 11); average particlediameter 3 μm; product of Titan Kogyo K.K.

Black pigment I: Copper Chrome Black Daipyroxide Black #9510 (PigmentBlack 28); average particle diameter 0.5 μm; product of DainichiseikaColor & Chemicals Mfg. Co., Ltd.

3 White pigments

Tipaque CR-90 (average particle diameter 0.4 μm); product of IshiharaSangyo Kaisha, Ltd.

4 Scaly substances

Mica powders MP-325 (average particle diameter 15 μm); product of OkabeMica Co., Ltd.

5 Spherical hollow substances Silica balloons QCEL300 (average particlediameter 5 μm); product of Asahi Glass Co., Ltd.

[Preparation of coatings]

1 Acrydic A-801P (acrylic polyol resin manufactured by Dainippon Ink andChemicals, Inc.) was used as vehicle in the proportion shown in Table 1and it was mixed with a solar heat-shielding pigment, dispersed in a 1:1mixture of xylene and methyl isobutyl ketone for 20 minutes and adjustedto 20 to 30 poises. Takenate D-170N (hexamethylene diisocyanate adductmanufactured by Takeda Chemical Industries, Ltd.) was added at the timeof application in such a manner as to make the mol ratio NCO/OH equal to1/1 to prepare Coatings 1, 2, 3 and 4.

2 Acrydic A-801P (acrylic polyol resin manufactured by Dainippon Ink andChemicals, Inc. ) was used as vehicle in the proportion shown in Table 1and it was mixed with a white pigment, a scaly substance and a sphericalhollow substance, then mixed with black pigment G until the hue becameN-7, dispersed in a 1:1 mixture of xylene and methyl isobutyl ketone for20 minutes and adjusted to 20 to 30 poises. Takenate D-170N(hexamethylene diisocyanate adduct manufactured by Takeda ChemicalIndustries, Ltd. ) was added at the time of application in such a manneras to make the mol ratio NCO/OH equal to 1/1 to prepare Undercoats 8 and9.

3 Coatings 5, 6 and 7 were prepared as in 1 except using black pigmentsG, H and I in place of the solar heat-shielding pigment.

Preparation of test specimens A 1 mm-thick soft steel sheet was coatedby spraying with Coating 8 or 9 to a dry thickness of 150 μm, dried at20° C. for 1 day, then coated by spraying with Coating 1, 2, 3, 4, 5, 6or 7 to a dry thickness of 50 μm and dried for 2 weeks to prepare a testspecimen.

[Method of testing]

The specimen was irradiated with an incandescent lamp as shown in FIG. 1and the temperature of the specimen at the reverse side was determined.The results are shown in Table 2.

With reference to FIG. 1, the procedure for determining this temperatureis as follows. A steel sheet 2 (measuring 150×70×1 mm) having a coat 1is fitted into a polystyrene foam block 3 having a thickness (t) of 30mm with the coat 1 facing upward. An incandescent lamp 4 (500-wphotoreflector lamp) is installed at a position 370 mm above the coatedsurface or h=370 mm and is connected to an electric power source 5. Atemperature sensor 6 is attached to the reverse side of the steel sheetand connected to a temperature recorder 7. The incandescent lamp 4 islighted while keeping the room temperature at 20°±1° C. and adjustingthe voltage of the power source 5 at 70±1 V and the temperature of thetemperature sensor 6 is recorded by the temperature recorder 7.

                                      TABLE 1                                     __________________________________________________________________________    Coating                                                                            Proportion of solids      Solar radiation                                No.  (% by weight)   Hue (Munsell)                                                                         L*                                                                              reflectance (%)                                __________________________________________________________________________    1    Vehicle      50 N-1     25                                                                              32                                                  Solar heat A 2.5                                                         shielding     B 1.5                                                                pigment    C 6.0                                                         2    Vehicle      50 N-1     25                                                                              34                                                  Solar heat A 4                                                           shielding     B 1.5                                                                pigment    C 4.5                                                         3    Vehicle      50 N-1     25                                                                              24                                                  Solar heat A 3                                                           shielding     C 1                                                                  pigment    D 6                                                           4    Vehicle      50 N-1     25                                                                              30                                                  Solar heat E 7                                                           shielding     F 3                                                                  pigment                                                                  5    Vehicle      50 N-1     25                                                                              0                                                   Black pigment G                                                                            5                                                           6    Vehicle      50 N-1     25                                                                              0                                                   Black pigment H                                                                            10                                                          7    Vehicle      50 N-1     25                                                                              2                                                   Black pigment I                                                                            10                                                          8    Vehicle      50 N-7     74                                                                              --                                                  White pigment                                                                              25                                                               Scaly substance                                                                            25                                                          9    Vehicle      50 N-7     74                                                                              --                                                  White pigment                                                                              40                                                               Spherical    10                                                               hollow substance                                                         __________________________________________________________________________

                  TABLE 2                                                         ______________________________________                                               Top- Under-   Test results                                                    coat coat     Reverse side temperature (°C.)                           No.  No.      Initial After one-year exposure                          ______________________________________                                        Example 1                                                                              1      8        73    73                                             Example 2                                                                              2      8        72    73                                             Example 3                                                                              3      8        78    79                                             Example 4                                                                              4      9        75    74                                             Comparative                                                                            5      8        96    96                                             example 1                                                                     Comparative                                                                            6      8        95    95                                             example 2                                                                     Comparative                                                                            7      9        93    94                                             example 3                                                                     ______________________________________                                    

INDUSTRIAL APPLICABILITY

As is apparent from the examples cited above, the temperature on thereverse side of the specimen indicates a marked heat-shielding effect.This invention thus contributes significantly to the progress ofindustries by making it possible to provide a solar heat-shieldingcoating composition which is applicable to the surface of ships and avariety of structures exposed directly to the sun to block the solarheat for a prolonged period of time, suppress the rise of insidetemperature, reduce the cost of air conditioning and suppress losses byevaporation of the contents for an expected effect of considerableenergy saving and also to provide a structure coated therewith.

What is claimed is:
 1. A solar heat-shielding coating composition whichcomprises a weather-resistant vehicle and 2 to 60% by weight based onsolids in the coating of a solar heat-shielding pigment consisting oftwo kinds or more of pigments selected from (A) red pigments with aparticle diameter of 50 μm or less showing a solar radiation reflectanceof 45% or more in the range from 350 to 2,100 nm as calculated from thespectral reflectance (R λi) specified by JIS A5759 for architecturalfilms for shielding heat rays and preventing scattering of shatteredglass, (B) orange pigments with a particle diameter of 50 μm or lessshowing the aforesaid solar radiation reflectance of 55% or more, (C)yellow pigments with a particle diameter of 50 μm or less showing theaforesaid solar radiation reflectance of 60% or more, (D) green pigmentswith a particle diameter of 50 μm or less showing the aforesaid solarradiation reflectance of 20% or more, (E) blue pigments with a particlediameter of 50 μm or less showing the aforesaid solar radiationreflectance of 20% or more and (F) purple pigments with a particlediameter of 50 μm or less showing the aforesaid solar radiationreflectance of 35% or more in such proportion as to yield achromaticblack of Munsell notation N-1 by additive mixture.
 2. A solarheat-shielding coating composition described in claim 1 wherein saidpigments selected from (A) to (F) are such as to yield achromatic blackby additive mixture.